What is the LCM of 3/4, 5/6 and 9/10?

Question 17

MediumOriginal question

What is the LCM of $\frac{3}{4}$ , $\frac{5}{6}$ and $\frac{9}{10}$ ?

\frac{1}{60}

Correct answerYour answer

\frac{3}{8}

Correct answerYour answer

\frac{45}{2}

Correct answerYour answer45Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

LCM of fractions = $\frac{\text{LCM of numerators}}{\text{HCF of denominators}}$ .
$\operatorname{LCM}(3, 5, 9) = 45$ .
$\operatorname{HCF}(4, 6, 10) = 2$ .
LCM = $\frac{45}{2}$ .

Worth noting

$\frac{45}{2}$ divided by each fraction gives a whole number: 30, 27 and 25. $\frac{3}{8}$ is $45 \div 120$ (LCM over LCM), which is smaller than the fractions themselves, so it cannot be a common multiple.

Concept: LCM of fractions
Typical timeTypical: 60 s
Your timeYours: —

The rule this testsFinding HCF and LCM

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Ten questions from HCF & LCM, at your own pace.

What is the LCM of 34\frac{3}{4}43​, 56\frac{5}{6}65​ and 910\frac{9}{10}109​?

Explanation

What is the LCM of $\frac{3}{4}$ , $\frac{5}{6}$ and $\frac{9}{10}$ ?